aftermarket ECU, coil-on-plug setup, swap tach assy or SS III cluster? Options

[match220]

Ok..look through this thread if you want to see my past attempts.

http://www.6gc.net/forums/index.php?showto...chometer+signal

In short, my temp gauge and tach gauge don't work anymore. The options I've thought about are (1) getting SS III gauges off ebay for $150 and swapping the odo, or (2) getting a cluster from an early 00's toyota car that has coil-on-plug setup from the factory and putting that tach in with my gauge face (may not be accurate).

Option 1 seems more doable, but I don't want to spend the $150 on gauges (PLUS I don't know if my wire harness connects to the SS III gauges, can someone tell me???) If so, all I would need to do is connect the tach wire from my Autronic ecu and configure, correct? Hopefully the wire connectors aren't needed.
Option 2 seems cheaper if I can find working used gauges on ebay. I'm concerned about the tach signal not lining up with the correct numbers (since I would have the moving parts from the donor car and the gauge face from mine). The only other downside would be that I still have to fix my temp gauge.

My only questions are about the interchangeability of the SS III gauges with the celica (manual trans GT convertible). And if anyone knows what other toyota models with coil-on-plugs would be good candidates for using the RPM gauge in the celica.